The portable microphone technology, called ShotSpotter, installed by a California-based company of the same name, uses the sound of a gunshot and acoustical triangulation to pinpoint the shooter’s exact location as a dot on a map and to alert a dispatch center.,In a 12-0 vote on Jan. 31, the Boston City Council approved the installation of bullet-detection technology in a five-mile area comprising parts of Dorchester, Mattapan, Roxbury and the South End.

The portable microphone technology, called ShotSpotter, installed by a California-based company of the same name, uses the sound of a gunshot and acoustical triangulation to pinpoint the shooter’s exact location as a dot on a map and to alert a dispatch center.

Gregg Rowland, Sr., vice president of sales and marketing for ShotSpotter, Inc. said since the affirmative vote, a contract is in the works between the city of Boston and the company.

Rob Consalvo, City Councilor for District 5, said he brought the technology to Mayor Thomas M. Menino’s attention last spring.

Since gaining his support, two public hearings and two live demonstrations at the Boston Police Department’s firing range on Moon Island in Quincy were held to educate city officials and citizens about ShotSpotter.

The $1.5 million technology is already at work in cities like Los Angeles, Washington D.C., Minneapolis and Rochester, NY, where Rowland said arrests for shooters have doubled and violent crimes have been reduced 30- to 35- percent.

Consalvo said the technology not only pinpoints the location of the gunfire within a two-mile radius but also tells police how many shooters there were, how many bullets were discharged, how many guns were used, if the shooter was driving or standing and what direction the drive-by car traveled after the shooting took place.

According to Rowland, ShotSpotter Inc. is working on a feature that would allow sensors to tell what kinds of bullets were fired as well.

Some residents, like junior media studies major Marissa Curry, don’t see a need for Shotspotter in their neighborhoods. “I lived in the South End my whole life and never felt unsafe,” Curry said, adding that she’d never heard of bullet detection technology. “Don’t they have more dangerous neighborhoods to [install] that in?”

Despite residents like Curry who feel safe, The Boston Globe reported on Jan. 6 that Boston had 54 gun-related homicides in 2006, a 10 percent increase over 2005 and that of 610 cases involving guns in 2006, only 23 percent resulted in the arrest or identification of a suspect.

“It’s so needed right now, even if it’s not a magic wand or a magic potion to stop violence,” Consalvo said. “This is showing the people of the city of Boston that the police have everything they need to do their jobs.”

Consalvo said that ShotSpotter shaves minutes off the average police response time in Boston which currently stands at six minutes. “Another great part is that Emergency Medical Technicians are on the scene of the gunshot too,” Consalvo said. “Every second counts in saving a life.”

In order to pay for ShotSpotter, the Mayor is using a $1.5 million supplementary appropriation which Consalvo said will not affect the currently balanced city budget.

“Tax revenue still comes in after we set the budget. The Department of Revenue for the state certifies that we get what’s called free cash which we can use for additional spending,” Consalvo said. “Obviously, we have to be cautious.”

Consalvo also said the mayor looks to spend the money on a one-time cost such as ShotSpotter and that the technology will be paid for with this surplus.

Besides concerns over cost, the technology raised civil liberties issues when it was proposed.

“People thought putting mics in areas would mean the government would be listening to voices,” Consalvo said. “The mics are so high-tech that they don’t pick up anything but gunfire. Even if they did pick up voices, no one would be listening.”

ShotSpotter is designed to ignore other loud noises like cars backfiring, fireworks and blanks.

Liam Green, a freshman Writing, Literature and Publishing major expressed concerns over Shotspotters installation.

“Last I checked, gunfire is pretty … audible; I hear it outside my window in the general vicinity of my building on a relatively regular basis,” Green, who lives in the Little Building, said. “But what else can they be used for? The obvious knee-jerk liberal answer would be to listen in on people, and the obvious defense would be, why would they bother? Personally, I don’t know . I can only say that this proposal freaks me out. Just a bit.”

Rowland said that the only problem he sees with the system is that it doesn’t detect what it doesn’t hear.

“If somebody shoots inside a building with the windows up it won’t detect it,” Rowland said. “Most violent crime is outside though. We pick up 90 percent or better of all shootings in the city which is 50- to 75- percent more than what they get with citizen calls.”

Rowland said that since implementing the system last month, Minneapolis has made six high profile arrests.

“The city also saves millions of dollars in prosecution fees.” Rowland said, “Most people who get caught take a plea because there is so much evidence against them.”

ShotSpotter also comes with the option to upgrade from microphones to cameras which Consalvo said Mayor Menino is looking into. Despite costs, Consalvo said it is an upgrade which he supports for the city of Boston.